Research and development of purifying catalysts not using noble metal as an essential component, are being carried out. There is known an exhaust gas purifying catalyst including a perovskite type composite oxide phase, which includes a rare earth element and a transition metal element and employs a perovskite type composite oxide in which part of the transition metal element is substituted with zirconium (refer to Patent Literature 1).
Further, there are known catalysts, such as a PM oxidation catalyst and an exhaust gas purifying catalyst, having an ability to highly store and release oxygen under low temperature and retain the ability for a long period of time (for example, refer to Patent Literature 2). Such catalysts include a composite oxide that has a perovskite type structure and contains a material with a high oxygen storage and release capacity at low temperature and a material with high oxygen mobility.